Identification of Mycobacterium avium subsp paratuberculosis infection in industrial dairy farms of Hamedan

John’s disease is a chronic intestinal infection which is caused by Mycobacterium avium subspecies paratuberculosis (Map) and imposes huge economic losses to farms. The aim of the present study was to detect infection by this bacterium in industrial farms of Hamedan. During the years 2015-2016, 150 fecal samples from apparently healthy and suspected cattle were collected and examined using direct microscopic and Nested-PCR assays. The results obtained from examination of fecal samples with Ziehl-Neelsen (ZN) staining showed that 8 samples (5.33%) were infected with the causative agent of the disease. While, using Nested-PCR assay, 39 and 9 samples were found to be positive in apparently healthy and suspected cattle, respectively. However, no significant difference was statistically observed between the numbers of positive cases in these two groups (0.05